Method of and device for improving gears



Sept. 8, 1931; E. WILDHABE 1,822,846.

I .l HETHOD OF AND DEVICE FOR IMPROVING GEARS Filed April 11. 192s 4 sheets-sheet 2 Sept 8, 1931 E. wlLlm-hflslan 1,822,846

METHOD 0F AND DEVICE FOR IMPROVING GEARS Filed April 17.11929 4 Sheets-Sheet 5 9a y los FIG-l1 as a6 96 u 1- a+ 97 10+ n fz 10o l \8 l I 95 INVENTOR v Sept. 8, 1931. E. wlLDHABER 1 1,822,846

METHOD 0F AND DEVICE FOR IMPROVING GEARS Filed April 17, 1929 4 Sheets-Sheet 4 11+ 2111+ 11 F|G-l5 in n 11o H11 i. 121 120 122 m11 F1217 Y 111 11s 118 111 f 12o" 12o. A m o 111 INVENTOR Patented Sept. 8, 1931 UNITED STATES PATENT OFF'IC'E I ERNEST WILDHABER, 'OE BROOKLYN, NEW YORK, ASSIGNOR ALO GLEASON WORKS, OF

ROCHESTER, NEW YORK, A CORPORATION F NEW YORK METHOD OFiAND DEVICE FOR IMPROVING GEARS Application led April 17,

The present invention relates to a methode of' and av device for improving gears, and particularly for improving gears by abraslon y of the tooth surfaces.

One object of the present -invention is to provide a method of and means for equalizing the tooth surfaces of gears in a simple vzo and efficient manner, and for removing spaclng errors or pitch errors of the teeth. 'i

and means for improving gears after hardening, and for edeeting equal and equally spaced tooth surfaces on said gears. Y

Another aim is to provide ways and means for simultaneously correcting both sides of the teeth of gears through abrasion in" a simple and efficient manner, comprising continuous mesh between a gear blank and two `rotary correction members.

A further object is to provide ways and means for improvin asset of equal gea-rs through abrasion wlth a toothed member which meshes successively with said gears, whereby the shape of the tooth surfaces of said member is derived from the tooth shape of said gears, and whereby the "teeth of said gears are equalized and spacing errorsremoved.

A still other aim is to provide ways and means for lapping a gear with a pair of toothed members, said members being suited to mesh with the two sides respectively of the teeth of said gear and being differently designed in a manner adapted to the diierent characterof mesh.

Aurther object of the present invention is to provide ways and means forl simultaneously abrading both sides of the teeth of a gear with two toothed members other than mating gears, by mounting said members on parallel axes angularly disposed t'o and offset Afrom the axis of said gear, and by rotating said'm'embers in abrasive engagement with the two sides respectively of the teeth oiI said gear. i

Another important obj ect of the present invention is to provide a method of and means for simultaneously abrading both sides of the teeth of a gear with two toothed members, whereby\ torque is transmitted to'said gearl A further object is to provide a method of f 1929. Serial N0.y 355,797.

through one of said members, and whereby.'

torque is regained from said gear through the other of said members, so that the resulting total torquev exerted on said gear is small and that the gear therefore does not require xvery rigid mounting, such as would consume considerable time.

' A further aim is to simultaneously abrade both sides of the teeth of la gear with two toothed rotary members operatively connected with each other, whereby one member transmits torque to said gear and the other member regains torque from said gear. With this arrangement thedriving motor needs to supply only the difference between the torque transmitted andlthe torque regained at the motor shaft, and can be kept small and inexpensive. Y A still other object is to correct a gear 1n a process in which the gear is continuously rotated on its axis and whereby continuous contact under pressure is maintained between said gear and a correcting member.

While the present invention will be particularly .described as applied to abrading.

tapered gears, it is understood that its principal features may also be applied to improving any other kind of gearing, such as worm gearing and gearing mounted on parallel axes, including straight spur gears, and helical and herringbone gears.

Various other objects will ap ear in theV course of the specification and rom recital of theapp-,ended claims. y

My invention will be described with embodiments illustrated in the accompanying drawings, in which l Fig. 1 is a plan view, partly in section, of a gear and-a toothed member in engagement With each other, for carrying out one embodiment of my invention.

Fig. 2? is a front elevational view correbroadly for correcting one-side of the teeth l of said gear. y

Fig. 4 is a'plan view, partly a section along,

lines 4 4 of Fig. 5, of the small gear or pinion, also shown in Fig. 3, in engagement with another toothed member.

Fig. 5 is a front elevational view corresponding to Fig. 4. Said other toothed member, indicated in Fig. 4 and Fig. 5, is differplanltory of a principle underlying several` -preferred embodiments of the present invention. y

Fig. 7 is a plan v1ew,partly a section along lines 7-7 and along lines 7 -7 of Fig. 8 of a device for improving gears in accordance with my invention. The device is shown somewhat simplified, some obvlous known details having been omitted.

Fig. 8 is a front elevational view of the same, and chiey a section along lines 8-8 of Fig. 9. l

Fig. 9 is a side View of the said device, a section along lines 9-9 of Fig. 8.

Fig. 10 is a partial rear view of the dev1ce,

and

4taken from the side of hand wheel 61 of Fig. 7'.

Fig. 11 and Fig. 12 are corresponding diagrammaticl views of an embodiment of my in-A vention adapted to improving tapered pmions or tapered gears of comparatively small taper. Fig. 11 is a diagrammatic'plan view,

shown 'partly in section, and Fig. 12 is a corresponding front elevational view, and a section along lines 12-12 of Fig. 11.

Fig 13 is a diagrammatic planview, partly in section, of a modified embodiment of the present invention. Y

fFig. 14 is a frontelevational view corresponding to Fig, 13.

Fig. 15 is a sectional viewv in an enlarged scale of a detail portion of the embodiment l illustrated in Fig. 13 and Fig. 14.

Fig. 16 is a view taken in the direction of arrow 16 of Fig. 15.

Fig. 17 is a diagram explanatory of an important feature of preferred embodiments of the present invention.

In Fig. 1 and Fig. 2, numeral 20 denotes a gear to be improved and numeral 21 vdenotes a rotary member containing teeth or threads 22 suited to mesh with the teeth 23 of gear 20. Preferably a plurality of teeth 22 are .provided on member 21. -Member 21 generally differs from the mating gear of gear 20. The latter may be for instancev a spiral bevel gear, in which case its mating gear or pinion is mounted on an axis intersecting the axis of gear 20, whereas axis. 24 of member 2l is offset from axis 25 of gear 20. The off- 24 insure sliding mesh between gear 20 and member 21, the teeth sliding lengthwise on each other, as known.

Member 21 is of such construction that a large number of its teeth 22 are in simultaneous contact with the teeth 23 of gear 20, and its tooth surfaces are conjugate to the tooth surfaces of gear 2O in such manner that the teeth 22 sweep the whole active tooth surfaces of gear 20 when member 21 is rotated in a single bodily position relatively to gear 20.

To obtain the mesh desired between gear 20 and member 2l an analysis of mesh may be made with the known methods of mathematics and kinematics, while considering the basic law formulated below:

Any point of a tooth surface of gear 20 can make contact with member 21 only when in such position, that a force extending along the tooth perpendicular at the considered point of gear 2O exerts turning moments about the axis 25 and about axis 24 in the Aset and the shownangular disposition of axis proportion of the numbers of teeth of gearl 2O and member 21. In other (words, to ob-.

tain the position of mesh with member 21 of Vany point of the tooth surface of gear 20, one may proceed as follows: The turning 4moment is determined, which is exerted on gear 20 by a unit force, which extends along the tooth perpendicular at any considered jpoint of the tooth surface of-gear 20. Differpendent of the angular position of gear 20, g

whereas the turning moment exerted by the same force with respect lto the anxis 24 of member 21 changes. The angular position of gear 20 is then computed, at which the said turning moment exerted with respect to axis 24 stands in the same proportion to the turning moment exerted by the same force on gear 20, as the numbers of teeth of member 211and gear 20 are to each other. l

Member 21 is to be rotated in abrasive engagement with gear 20, as will be further described hereafter.

Preferably the two sides of the teeth (23) are improved or corrected with different members (21), whose design, number of of teeth, and amount and direction of offset are adapted to the given side of the teeth.

This is further illustrated in the Figures 3 to 5. A gear 27 of small taper angle, usually termed a pinion, may be improved with two different toothed members 28, 29 which are conjugate to the two sides respectively of the teeth of gear 27. The members 28 and 29 are differently offset from the axis 30 of gear 27, one (28) being offset in a direction corresponding to an increased inclination of its teeth 31, as compared with the teeth 32 of gear 27, and the other member (29) beingv offset in a direction corresponding to a reduced inclination of its teeth 31. In the instance illustrated in Fig. 3 to Fig. v5, a comparatively lar e arc of action between gear 27 and a mem er 28 or 29 may be obtained,.

by providing a member 28 for engaging the lengthwise concave side 33 of the teeth 32 of gear 27; and by providing a member 29 for engaging the lengthwise convex sides 34 of the teeth 32 of gear 27. A large arc of action, resulting'in a large number of teeth in s1- multaneous contact, is often very desirable,

as will be lfurther described hereafter. The ,increased arc of action is in the illustrated instance furnished chiefly through the profile action of the teeth. It is known that' the profile, action is different on the two sides of.

the Ateeth of tapered gea'rsliaving angularly disposed and offset axes.. In the combination illustrated by Fig. 3, the concave side 33 of the gear teeth contains a long profile action,

. and the convex side 34 of the gear teeth would f sive engagement with the convex tooth sides 34 of gear 27, a comparatively long profile action maybe obtained in either case.

The use of different members (28, 29) for correcting the two sides of the teeth is not conlined to the correction ofgears-(27) of small taper angle, but ma of course also be applied to the correction'of gears of large taper angle, and to gears in general.

The chief reason for desiring a long ar/c of action between a gearA and its conjugate rotary member `will now be explained with reference to diagram Fig. 6. In Fig. 6, numeral 36 denotes a portion of a gear and numeral'37 a portion of a member engagingsaid gear in abrasive contact. For convenience theteeth of member 37 have been shown compleinentary to the teeth of gear 36. rllhis was deemed permissible lin view of the diagrammatic nature of Fig. 6. The feature to be illustrated by Fig. 6 is the large number of teeth 38 of member 37 in simultaneous contact with the teeth 39 of gear 36, regardless of the exact nature of the contact. As a rule the teeth of gear 36 are conjugate to, but not complementary to the teeth of member 37. Gear36 contains teeth of vvarious degrees of accuracy, and for the sake of explanation twotooth surfaces, 39 and 39, are assumed as protruding over the rest of the tooth surfaces inthezone of contact. As a result of their provantages, such as the use o truding position, the tooth surfaces 39fand 39" alone make contact with the teethl 38, as indicated in Fig. 6, while the other tooth surfaces recede somewhat from the mating teeth. This feature forms the basis. of a self correction, as will now be briefly explained,

and has been explained at length in my pending application entitled: Method of and v means for perfecting gears and gear-shaped articles, filed February 11, 1929, Serial No. 339,018. v l

When a suitable fine abrasivefsuch as alapping compound, is provided between the contacting teeth 38 and 39, and when the gear 36 and member 37 engage in sliding mesh, only/the contacting tooth surfaces will wear down through abrasion. Referring to gear 36, only the sides 39 and 39 -will be subject to abrasion in the illustrated position. When several teeth are in simultaneous mesh, it is not necessary to positively gear up the correction member and the gear to beimproved and esI are gradually madel all alike and spacing errors are removed. The sparing errors are known to be the most objectionable errors, and these are directly eliminated. How further corrections may be effected will be described hereafter.

The correction and equalization of the tooth surfaces is the more rapid andthe more .complete, the larger the number of teeth is, which are simultaneously in the zone of mesh. It is therefore obvious that it is desirable to eflfect an arrangement, in which `a comparatively large number of teeth are in simultaneous contact, and in which the arc of action is long. rlthis may be done in accordance with the present invention by providing two different correction members, which are suited to mesh with the two sides respectively of the teeth of a gear to be improved, land of which each one is specifically adapted to its different mesh. Furthermorev the provision of different members for correcting the two sides of the teeth permits to secure other adf members of maximum eliiciency and diameter.

4In a preferredembodiment of my inven tion two rotary toothed correction members are provided, and rotated in simultaneous abrasive engagement with a gear to be improved, which may be referred to as a gear blank. The advantages obtained with such arrangement are not confined to a savingof time, butanclude a reduction of power con- "sumption While maintaining a simple design, Aand the elimination of the necessity of very rigidly holding'the gear blank. These and other features' will be understood from the description of an embodiment, which will now be madev with referencel to the Figures -izo Gear 45, -which may be referred to as gear.

blank, is mounted on a shaft 47, which carries a projection 48,.closely fitting the ,inside surface of gear 45. Projection 48 forms part of an arbor 50,.which is secured to shaft 47` by a taper fit 51 and by a screw 52 for tight# or inspected.

eniug said taper fit. Further connection between projection 48 and shaft 47 may be effected, if so desired, by means of taper pins 53. tion with shaft 47 through the friction between its inside surface and the closely fitting projection 48. On account of the arrangement provided, no appreciable amount of torque is transmitted between gear 45 and shaft 47, so that the said simple frictional connection is suiiicient to hold the gear on shaft 47.

The back of the gear lbears against@ disk 54, which is formed-integral with shaft 47, and Which-also serves to protect the bearings 55, 56 of shaft 47 from the abrasive compound or other material used in the improving operation on the teeth of ear 45. l

End play of shaft 4 may be avoided in known manneriby a spring 57,`which tends to axially separate the bearings 55, 56, and maintains them under axial pressure. The

'bearings 55, 56 are mounted on a slide 58,

which maybe locked to bed 59 during the perfecting operation, withn any suitable known means omitted lin the drawin s. Slide 58 is movable along guides 60 o motion beingefifected with a `hand wheel 61 operatively connected with slide 58.- By turning hand wheel 61, gear 45 may be withdrawn from engagement with the rotary members 41, 42, so that it may be replaced The erfecting members 41, 42 are differeutly o set from thecenter of gear 45; and they contain different diameters'and differont numbers of teeth. In the disposition specifically illustrated, the smaller member 41is preferably used for meshing with and perfecting the concave 4sides 62 of the teeth of gear 45. And the larger member 42 is Gear 45 is maintained in constant relabed 59,

preferably used for meshing with and pei"- fectmg the convex sides 63 of the gear teeth. The members 41, 42 are rigidly secured to the respective shafts 43, 44, by means ofl screws and keys, the latter being omitted in thedrawings. Shaft 43 is mounted on a stationary casing or frame 64 by means of bearings 65 embodied here as ball bearings. Adjacent its outside end, shaft 43 contains a pulley 66 rigidly secured to said shaft. Motion may be imparted to said pulley by means of aV belt 67, which may be driven for instance with a motor disposed in the frame of the device, or in any other suitable known manner.

Shaft 44-is mounted on two bearings 68. A gear 7 O is loosely mounted on shaft 44 and frictionally connected with said shaft by means of a disk clutch 71, which permits 0f relative sliding between the gear and shaft 44. Clutch 71 contains a disk or a plurality of disks 72 which are axially movable but 4angularly fixed to a cup shaped extension of gear 70. Other disks 73 are angularly fixed-to 'shaft 44 by means of splines. The disks 72, 73 frictionally engage each other under pressure, the pressure being supplied by a spring 74, which acts on a ring 75 bearing against gear 70, and which presses the clutch against the inner race of a ball bearing 68. The latter is rigidly secured to shaft 44 'b` means of a nut engaging a threaded portion of shaft 44.

The pressure of spring 7 4 may be adjusted by turing a nut 76, which engages another threaded portion 77 of shaft 44.

Gear 7 0 meshes with another gear 78 forming part of shaft 43, and the two gears' 70, 78 thereby form an operative connection bctween the members 41, 42 or their shafts 43, 44.

The members 41, 42 are also operatively -interconnected through their` mesh with optransmitted from one of the members 41, 42 Y to gear 45,'and from gear 45 to the other vof said members 41, 42. The small amount of' slippage on the other hand prevents any appreciable loss of energy.

The described generaarrangement is eilicient, inasmuch as both sides of the teeth of gear 45 are simultaneously acted upon by the two members 41, 42 respectively, and it is further economical in that only the energy conv sumed through friction needs to be imparted to pulley 66.

The ratio between the gears 70, 78 may be made slightly vlarger or slightly smaller than the ratio of the tooth numbers of members 41,` 42. If pulley 66 is rotated in a clockwise direction, that is to say in the direction of arr-ow 80, the ratio of the numbers of teeth of gear 70 and gear 78 should be made smaller than the ratio of the numbers of teeth of members 42 and 41, when it is desired to en gage the convex tooth sides 63 with member 42 and the concave tooth sides 62 with member 41. It is readily understood that the difference in the ratio of the positive operative connections determines the direction of pulley 66 is rotated in counterclockwise direction, that is to say ina direction opposite A:se

to arrow 80, the ratio of the numbers of teeth of gear and gear 78 should be made larger than the ratio of the numbers of teeth of member 42 and member' 41. Such provision will keep member 41 in engagement with the concave tooth sides 62 and member42 in engagement with the convex tooth sides 6 3. .y

- Abrasive compound or an equivalent substance may be applied to the intermeshing teeth in any suitable known manner. A cover 8l prevents the abrasive or lapping compound from being thrown olf and keeps the .surroundingsof the device clean. The housing containing the gears and shafts 43, 44 is preferably composed in known manner of a plurality of parts securely fastened together, to facilitate assembly. An upper part of said housing is denotedwith numeral 64. The shape of the housing is adapted to its purpose and does not form part of the present invention. n Y

In operation a plurality of equal gears are successively mounted' on shaft 47 in place of the gear denoted with numeral 45, and rotated in engagement with the members 41, 42, each of which engages one of the two sides of lthe teeth of said gear. Rotation is effected preferably in a single bodily position betweenv gear l45 and members 41, 42, whereby said members mesh with the entire tooth surfaces of the gear 45. On account of the large number of teeth in simultaneous mesh between gear 45 and each memberr41, 42, the tooth surfaces are rapidly equa-lized, andprotruding tooth surfaces are worn down. While the members 41,42 are alsosomewhat subject to abrasion, they remain conjugate to the gears, and their tooth shape is maintained through successive mesh with a plurality of gears having equal average tooth surfaces. As wear proceeds vthe members 41, 42 -so to say obtain their tooth shape from the gears with which they successively mesh. Their correction action does not consist in forcing a specific tooth shape on the gears, but in equalizing the existing teeth and in removing pitch errors. Changes in the tooth shape are preferably effected in the preceding cutting operation, in a mannerd known in the art.

The members 41, 42 do not need to be trued as is the case in conventional grinding operations or abrasive operations. rIhey are run equal periods successively with a plurality of equal gears 45, until said members are nearly used up. 'Ihe members 41, 42 are then replaced-by new ones.

In the embodiment indicated in the Figures 11 and 12, numeral 82 denotes a gear of small taper, often called pinion. Gear 82 is rotatably mounted on a slide 83, which may be secured to stationary base 84 by means of screws' passing through holes 85, and which may beA moved along guides 86 of base 84. CIn the position indicated in Fig. 11 and Fig. 12, gear 82 engages two toothed correction members 87, 88, each of which is suited to mesh with one side of the teeth of gear 82. Members 87, 88 contain preferably different numbers of teeth and moreover teeth of different inclination with respect to vthe straight generatrices of their pitch surfaces, as expwl'amed with respect'to members 28 and 29,

1g. 3 to Fig. 5. As a rule members 87, 88 are mounted on parallel axes (90, 91), but in somecases they may be mounted on concentric axes` 90, 91, as indicated in the drawings. The axes or shafts 90, 91 .are mounted in bearings 92, 93 which are supported by statlonary portions omitted in the drawings. Grearsi 94, 95 are rigidly secured to the two shafts 90, 91 respectively. Motion is imparted to' a pulley 96, which is keyed to a shaft 97 in a manner permitting slight axial displacement. Shaft 97 is mounted in bearings 98, 99. Adjacent one end o-f shaft 97, a gear 100 is rigidly secured to it, as diagrammatically indicated in Fig. 12.l Gear 100 meshes with an idler 101, which in turn meshes with gear 95. Adjacent the other end of shaft k97, a gear 102 is losely mounted on' it and bears axially against a disk like 103 itigidly secured to shaft 97. ear 102 is frictionally connected with pulley 96 by means of a multiple disk clutch, which consists of disks splined to the hub of gear 102, and of other .disks splined internally to a hollow projection of pulley 96. The disksof the two sets alternate with each other, as well known. Pressure between the engaging frictional surfaces is eifected-by a spring 104, which acts on pulley 96, and which is adjustable by means of a nut 105. Said nut engages a threaded portion of shaft 97. The ratio of the gear train 94, 102 v100, 101, 95 is made slightly different from the ratio of the numbers of teeth of the two members 87, 88, and

rojection los no I

the operation of this embodiment is analogous to the' operation described with refershown gear blanks and rotary members mounted on axes disposed at right angles to each other, it is clearly understood, that I do not wish to confine myself to such disposition, and that a correction member and a gear blank may also be mounted onaxes disposed at other angles, and especially at obtuse angles to each other. Inl the latter case a correction member would` contain a larger taper and could be made of larger size than for instance member 21 of Fig. 1 and Fig. 2. If so desired, the angle between theA axes 24 and 25 can beV increased to such an amount, that member 21l assumes the shape of a crown gear,

or even of an internally toothed member. Member 21 assumes the shape of a crown gear (with oiset'laxis); when the anglebetween the axes '24 and 25 equals ninety deg'rees plus the pitch angle of gear 20. And member 21 assumes the sha e of an internally toothed tapered gear, w en the angle between the axes 24, 25 is incrgased above said amount.

The latter case contains advantages especially when the pitch angle of the gear (2O or 27) is comparativel small.

vA further em odime'nt of my invention will now be described with reference to Figures 13 to 16. While this embodiment is broadly applicable, it is especially adapted to gears of such structure that a large number of simultaneously meshing teeth cannot, be secured Without diiiiculty.

A gearor pinion 110 to be corrected is mounted on an arbor 111 which is secured to Les a hollow shaft 112 of such inside diameter,

that gear 11() may be placed in position by advancing it through said hollow shaft. Gear 110 engages a correction member 113 secured to a drum 114, which contains a pulley 115 'and which is mounted in bearings 116, 117

disposed in drawm stationary portions omitted in the Anote'r'gear 118 is rigidly secured to a ypro'ection of drum 114 and meshes with a pinion 120 formed integral with hollow shaft 112. Pinion 120 and ear 118 constitute an operative 'connection etween the members connected with shaft 112 and drum 114, in addition to the operative connection'provided by gear 110'and member 113. In the l present instance, the gear pair 120,118 are in the nature of master gears, as will be further described hereafter, and contain preferably theexact ratio of the numbers of teeth of the pair 110, 113. Shaft 112 is mounted in bearmgs 121, 122 which are heldin place by suitable stationary projections of known character. A cup shaped member 124 is rigidly secured to shaft 112 adjacent its outward end, see alsoFig. 15 and Fig. 16. Member 124 contains internal splines, with which engage a plurality of disks 125, in a manner to be axially movable but angularly fixed to said member. Other disks 126 alternate with the first said disks. Said other disks are se cured to'splinesof another member 127, which is axially las well as angularly movable on shaft 112. Pressure of'engagement of disks 125, 126 may be effected by turning a nut 128, which engages a threaded portion of member 127. .The whole unit, comprising disks 125, 126 and member 127 is pressed in axial direction by means of a `spring 130, whose'pres.

sure may be varied by turning n ut 131. If

so desired, spring 130 may be disposed in known manner to act directly between member 127 and nut 131. Adjacent-'its front end member 127 contains helical slots 132, which fit projections 133 provided, on arbor 111. Projections 133 are indicated in dotted lines in Fig. 13 and Fig; 15, and are provided with helical sides contacting with the helical sides of slots 132. The slots 132 may be well seen on the left hand side of F 16, where arbor 111 has'been omitted. The right hand side of Fig. 1 6 shows the arborlll in place,and

clearly indicates the said projections 133. A

-screw 134, or a plurality of screws, serves to limit the axial path of member 127, and

also for withdrawing said member against the action of spring 130. In the present embodiment, the clutch formed by ,member 124,

.member 127 and disks'125, 126 serves to permit. angular displacement between arbor 111 and shaft 112, to aid in setting a gear blank 110 in engagement with toothed member 4113 prior to the correct-ion or perfecting opera-- tion. i Before and during the perfecting operation, the said clutch is tightened by turnpressure of spring 130 is set, and accordingly the pairs 110, 113 and 118, 120 engage un a larger or a smaller pressure depending on` the adjustment of nut 131. Pinion 110 and pinion 120 engage their respective members or mating gears on oppositesides of the teeth.

The hand of the helical slots 132 and helical' projections 133 determines the side of the .teeth of inion 110 which is in engagement and whic is being operatedon. -To operate on both sides of the teeth of gear 110, two devices are used, which contain slots 132 of opposite hand.

Fig. 17 illustrates the manner of effect-ing pressure in the intermeshing teeth. The two portions 110 and 120 diagrammatically denote portions of the coaxial pinions 110,120.

A tendency to'angularly move the two Apinions relatively to each other for instance in a direcspring 130, whereas nut 128 has been loosened.

After pinion 110 has been set, nut 128 is motion to pulley 115. Pinion 110 tightened to fuly engage the clutch so as to form a rigid frictional connection between members 124 and`127. A

Screw 134 is then'turned back from engagement with the end portion of shaft 112- an amount corresponding to the desired total axial travel of member 127 during the perfecting operation. The said travel is a measure of the desired total angular displacement of the pinions 110 and 120 during the perfecting operation, and also of the amount of stock to be removed.

, The rotary members mounted on shaft 112 and drum 114 are then turned by applying and pinion 120 are thereby maintained in engagement under pressure.with member 113 and gear 118 respectively. Abrasive or lapping compound 4is provided on the intermeshingteeth of pinion 110 and member` 113, but kept away from pinion 120 and gear 118. rllhe pressure of vengagement continues until abrasion or wear has occured to such an extent, that member 127 has gradually come up to the stop provided to limit its axial travel, that is to say the pressure continues until screw 134 hits the end of hollow shaft 112. UThe two members are then further rotated acer,- tain time until protruding tooth surfaces of pinion 110 have been abraded and equalized so that none of the tooth surfaces of pinion 110 is capable of momentarily restoring pressure of engagement.

1n practice it is found important-that the operative connection through helical surfacesbetween member 127 and arbor 111 should not be self locking. 1t is kept well lubricated or greased, and if so desired antifriction means of well known character may be provided, to further insure that the operative connection may be operated both ways. ln other wordsit is desirable to take vcare that sufficient torque exerted on arbor -sav for the pinion 110 to be improved, as

will be readily understood from the above description. Numerous changes and further i modifications may be made in my invention without departing from its spirit, by simply applyingthe established practiceand customary knowledge of the art., For definition of the scope of my invention, itis relied upon the appended claims. y

What I claim is: t f

l. The method of improving tapered gears whose pitch surfaces roll without sliding on the -pitch surfaces of their .mating gears,

which consists in providing a tapered gear and a pair of rotary toothed members suited -to mesh with the two sides respectively of in rotating said members in abrasive engagement with the two sides respectively of the teeth of said gear.

3. rllhe method of improving gears, which consistsin providing a gear and a pai-r of toothed members suited to mesh with the two sides respectively of the teeth of lsaid gear, in mounting said members on parallel axes angularly disposed to and offset from the axis of said gear, and in simultaneously rotating said members in abrasive engagement with the two sides respectively of the teeth of said gear.

4. rlhe method of improving gears, which consists in providing a gear and a pair of toothed members conjugate to said gear, in

`disposed to and oii'set from the axis of said gear, in rotating said members in simultaneous abrasive engagement with the two sides respectively ofthe teeth of said gear, in transmitting torque from one of said members to said gear and from the gear to the other of said members, and in transmitting torque lfrom said other member to the first said memer. 5. The method of improving gears, whichA consists in providing ajgear and a pair of toothed members conjugate to said gear and suited `to engage in sliding mesh with said gear, in mounting said membersand said gearsadjacent each other, in rotating said members in simultaneousabrasive engage-- ment with the two sides respectively of the teeth of said gear, and in transmitting torque from one 4of saidv members to said gear and from said gear to the other of said members,

. thereby balancing the pressure exerted on one side of the teeth of said gear with pressure exerted on the other side-of said teeth. Y 6. The method of improving gears, which sivo engagement with the two sides respectively ofthe teeth of said gear, and in operatively interconnecting said members.

7. The method of" improvinfr curvedptooth taperedgears, Whiclrconsists 1n providing a curved tooth tapered gear and a pair of difthe two sides respectively Yferent toothed membersgconjugate to said gear and suited to engage irpfslilding meshftwiti o t e teeth o sai gear, in mounting said gear and said members on angularly disposed and offset axes, in rotating said members in simultaneous abrasive engagement with the two sides respectively of the tee'.h of said gear, and in operatively interconnecting said members.

8. The method of improving gears, which consists in providing a gear and a' pair of toothed members conjugate to ,said gear, in mounting said gear and said members on angularly disposed and offset axes, in rotating said members in simultaneous abrasive engagement with the two sides respectively of the teeth of said gear, and in operatively and yieldingly interconnecting said members.

9. The method of improving tapered gears, which consists in providin a tapered geap and a pair of toothed mem ers conjugate to said gear, in providing turnin motion between vsaid gear and said toot ed 1members about the axis of said gearand the axes of said members, the axes f said members being angnlarly disposed o and oset from the axis of said gear, 'in rotating said mem-` beis in simultaneous abrasive engagement with the .two sides respectively of theteeth of said gear, and in operatively interconnecting said members.

10. The method of improving gears, which consists in providing a gear and a pair of rotary members suited to engage 1n sliding mesh with the two sides respectively of the teeth of said gear, in rotatably mounting said gear and said members on oset and angularly disposed axes, and in sweeping the whole active tooth surfaces of said gear per revolution of said gear while rotating s aid members in abrasiveepgageinent lwith* said ear. 4 g 11. The method of improving gears, which consists in providing a set of equal gears and a rotary toothed member conjugate to said gears, in successivelyY rotating said member in abrasive engagement with said equal gears on an axis angularly disposed to and oEset ,from the axis of a gear for equalizing the teeth of said gear, and in controlling the tooth surface shape of said member exclu- Vgear blank and a toothed member mounted on axes offset fromv and angularly disposed.

to each other, means for rotating said member and said gearblank in abrasive engagement with each other, another operative connection between said memberand said gear blank, and means for setting-v the pressure of abrasive engagement.

13K In a device forv improving gears,- a gear blank' and a toothed member mounted on raxes offset from and angularly .disposed to each other, nieans for rotating said mem'- ber and said gear blank in abrasive engagement with each other, another operative connection between said member and said gear blank, said other operative connection comv ,prising positive operating means and frictional means. 14. In a device for improving gears, a gear blank and a toothed member mounted on axes offset from-'and angularly disposed to each other, means for rotating said member and said gear blank i abrasive engagement with each other, anoiilier operative connection between" said member and said gear blank, said other operative connection comprising positive operating means, frictional ting the pressure of frictional engagement of said clutching means.

15. In a device for improving gears, agear blank, a pair of toothed members `mounted on axes oiset from and angularly disposed to the axis of said gear blank, said members meshingwith the two sides respectively of the teeth of said gear blank, means for rotating said members in simultaneous engagement with said gear'blank, and Vmeans for effecting pressure between the interen- `gaging teeth of the gear blank and said members.

16. In 4a device for improving tapered gears, a tapered gear blank, a pair of toothed members mounted on parallel axes 'offset from and angularly disposed to the axis of members in simultaneous abrasive engage- `ment with the two sides respectively of the rotating gear blank, and another operative connection between said two members, said other operative connection comprising positive operating means corresponding to a ratio differing from the ratio of the numbers of teeth of said two members'and rictional clutching means.A

17. In la device for improving tapered gears, a taperedgear blank, a pair of toothed members conjugate to said gear blank and mounted on axes offset from and angularly disposed to the axis of said'gear blank, means for rotating said members in simultaneous abrasive engagement with the two sides relao -with each member,

" bers is controlled by /ing in engagement .conjugate to said gear League spectively of the teeth of said gear blank, and another operative connection between said two members, said other operative connection containing frictional clutching means and spring means for maintaining said clutching means in engagement under pressure.

18. The method of improving gears whose pitch surfaces roll without sliding on the pitch surfaces of theirgmating gears, which consists in providing a gear and a pair of rotary toothed members suited to mesh with t-lie two sides respectivelyo the teeth of said gear in a niannerthat continuously a plurality of gear teethA are inengagement in mounting said members on axes oii'set from and angularly disposed to the axis o said gear, and in rotating said members in abrasive engagement with the two sides respectively of the teeth' of said gear, so that the relation between the lturning angles o f said gear and of said memthe tooth surfaces of said gear and said members, each member bewitli one of said sides onl a 19. The method of improving gears after hardening, whose pitch surfaces roll without sliding on the pitch surfaces of'their mating gears, which consists in providing a gear and a plurality of rotary toothed members and suited to engage in sliding mesh with the teeth of said gear, a plurality ofteeth of each of said members being in contact with said gear throughout said mesh, in mounting said gearA and said members on angularly axes,'land in rotating said members in simultaneous abrasive engagement with said gear, so that the relation between the turning angles of said gear and of said members is controlled by the tooth surfaces of said gear and said members.

20. The method of improving gears after hardening, whose pitch surfaces roll without sliding on the pitch surfaces ot their mating gears, which consists in providing a gear and a plurality of rotary toothed members conjugate to said gear and suited. to engage in sliding mesh with the teeth of said gear, a plurality of teeth of each o said members being in contact with said gear throughout said mesh, in mounting said'members on parallel axes angularly disposed to and offset disposed and oiisetvn tact with said teeth of said gears are inclined to4 their peripheral direction, in mounting said member adjacent one of said gears on an axis angularly disposed to aiid offset from the axis of said gear, in rotating said member and said gear in abrasiveengagement with each other, and in repeating the aforesaid steps on other gears until the tooth thickness of said member Y at a given radius and axial position has' been reduced at least ten percent.

22 The method of improving gears after 'niA hardening, whose pitch surfaces roll without 'sliding on the pitch surfaces of their mating gears, which consists in providing equal gears and a rotary toothed member suited to engage in sliding nieshwith said gears, a tooth of said member being less inclined to the peripheral directionof said member than the teeth of said gears are inclined to their peripheral direction, in mounting said member adjacent one of said gears on an axis angularlyv disposedv to and oiset from the axis of said gear, in rotating said member in abrasive engagement with one side of the teeth of said gear. and in repeating the aforesaid steps on other gears with the axis of said member oiiiset the. same amount from the gear axis, until the tooth thickness on vthe outside-of said member has been i'educed at least ten percent. 23. The method of improving gears after/ hardening, whose pitch surfaces roll on the pitch surfaces of their niating'gears, which consists in providing equal gears and a rotary toothed member fully conjugate to said gears and suited to mesh with line congears, inniounting said member adjacent one of' said gears on an axis angularly disposed to and oti`set from the axis of said gear, in rotating said member in abrasive engagement with one side of the teeth ot said gear, and in repeating the aforesaidsteps on other gears with the axis of said member offset the same amount from thegear axis. until the tooth thickness on the outside of said member has been reduced at least ten percent.

\ ERNEST wnmHai-ina.

from theaxis of said gear, and in rotatingj ripheral direction of said member than the 

